[FFmpeg-cvslog] avcodec/diracdec: Fix integer overflow in mv computation

[Michael Niedermayer]

ffmpeg | branch: release/2.8 | Michael Niedermayer <michael at niedermayer.cc> | Sun Feb 18 21:51:38 2018 +0100| [84bf347ff054a928e69debb3d84b7c4f9d1a832e] | committer: Michael Niedermayer

avcodec/diracdec: Fix integer overflow in mv computation

Fixes: signed integer overflow: -2072 + -2147483646 cannot be represented in type 'int'
Fixes: 6097/clusterfuzz-testcase-minimized-5034145253163008

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 47e65ad63b3d067445c4de41a7718b83fc07767c)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=84bf347ff054a928e69debb3d84b7c4f9d1a832e
---

 libavcodec/diracdec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/diracdec.c b/libavcodec/diracdec.c
index fb54312c49..9801eb2c85 100644
--- a/libavcodec/diracdec.c
+++ b/libavcodec/diracdec.c
@@ -1224,8 +1224,8 @@ static void decode_block_params(DiracContext *s, DiracArith arith[8], DiracBlock
                 global_mv(s, block, x, y, i);
             } else {
                 pred_mv(block, stride, x, y, i);
-                block->u.mv[i][0] += dirac_get_arith_int(arith + 4 + 2 * i, CTX_MV_F1, CTX_MV_DATA);
-                block->u.mv[i][1] += dirac_get_arith_int(arith + 5 + 2 * i, CTX_MV_F1, CTX_MV_DATA);
+                block->u.mv[i][0] += (unsigned)dirac_get_arith_int(arith + 4 + 2 * i, CTX_MV_F1, CTX_MV_DATA);
+                block->u.mv[i][1] += (unsigned)dirac_get_arith_int(arith + 5 + 2 * i, CTX_MV_F1, CTX_MV_DATA);
             }
         }
 }